Chris
Good question but it never came up in my career.
Yes, the fin is laterally symmetrical and mounted symmetrically.
Like FlightDetent I can't see any reason for a yawing force if the engines are being operated symmetrically
PilotJames
I haven't read the FCOM so this may be complete nonsense, but if the average offset were between 0.5 and 0.8 left (which is more sensible than 0.5R to 0.8L if it is really a one-way temperature effect) then the 1R/2.3L would also make sense wouldn't it?